1. Technical Field
The present invention relates to a robot control device, a robot control method, a robot control program, and a robot system.
2. Related Art
In order to control an arbitrary position and a posture of a hand of a robot, the robot needs to have at least 6 axes of motion. Moreover, the robot needs to include at least 7 axes of motion to avoid a singular point or an obstacle when an arbitrary position and a posture of the hand of the robot are controlled.
JP-A-2005-193311 discloses a method of controlling a robot including 7 axes. The control method includes numerically obtaining a redundant axis that is rotated to avoid a singular point and the rotational amount thereof is controlled using an iterative method.
JP-A-7-132474 discloses another method of controlling a robot including 7 axes. This control method includes automatically selecting at least one of the 7 axes as an axis for avoiding a singular point (so as to be regarded as a 6-axis robot), and solutions that define joint angles corresponding to the position and the posture of the hand are analytically obtained by inverse kinematics. Thus, the amount of calculations is reduced and the robot may be operated at high speed.
However, in the method of controlling a robot described in JP-A-2005-193311, since the iterative method is used, there are problems in that there is a large amount of calculations and thus it is difficult to operate the robot at high speed.
In addition, in the method of controlling a robot described in JP-A-7-132474, there are problems in that the position corresponding to an elbow may not be explicitly designated and instructions for an operation of intuitively avoiding an obstacle may not be performed. Further, an axis corresponding to the shoulder may not be defined, and thus there is a problem in that the method may not be applied to a robot including an offset structure between, for example, a first axis and a second axis.